Despite an increased awareness of the relevance of psychobiology and psychopharmacology to the care of ethnic minority mental health patients, and the growing recognition of substantial ethnic and cultural diversity in psychobiological processes and responses, relatively few controlled investigations have been conducted to examine these issues. Results of such studies are important not only for the clinical care of patients with divergent ethnic backgrounds, but also have significant basic science implications. In order to continue addressing these important clinical and theoretical issues in a systematic manner, this application seeks continued support for the Research Center on the Psychobiology of Ethnicity. Building on the solid foundation of the infrastructure, research models, and collaborative networks that have been established, the Center will continue to foster and promote research on issues relevant to the interface between ethnicity and psychobiology. Innovative research designs and state-of-the-art methodologies including those derived from pharmacogenetics, molecular biology, brain imaging and chronobiology will be utilized to further delineate mechanisms underlying ethnic differences (and similarities) in psychotropic response, to examine the psychobiologic and nosologic status of "culturally specific syndromes" and their relationship to existing DSM-III-R and DSM-IV diagnoses, and to explore other psychobiologic and psychopharmacologic issues in the context of ethnicity and culture. During this funding cycle, six Center-initiated projects will be implemented. These include: (1) Mechanisms of Ethnic Difference in Psychotropic Responses; (2) Ethnicity, Brain Imaging and Antidepressant Response; (3) Psychiatric Diagnosis and Biological Markers in Patients with Neurasthenia, Chronic Fatigue Syndrome and Depression; (4) Ethnicity and Tardive Dyskinesia; (5) Whole Blood Serotonin in Mental Retardation: Ethnic Influences; and, (6) The Effect of Caffeine on Cerebral Perfusion in African-Americans and Caucasians. In addition, a number of explorative projects will be developed throughout the duration of the grant. The activities of the Center, with its primary focus on psychobiologic issues, will complement other research on ethnic minority groups that are predominately psychosocial in nature, and help to ensure that our efforts in understanding issues confronting the rapidly increasing ethnic minority populations are comprehensive and encompass the entirety of the biopsychosocial model.